microsoft/autogen · error · ValueError

Invalid subscription message.

Error message

Invalid subscription message.

What it means

subscription_from_proto converts an incoming protobuf Subscription message back into an AutoGen Subscription by inspecting the `subscription` oneof field. If the oneof is unset (None), the message is malformed and the function raises ValueError('Invalid subscription message.') rather than guessing a type.

Source

Thrown at python/packages/autogen-ext/src/autogen_ext/runtimes/grpc/_utils.py:45

    oneofcase = subscription.WhichOneof("subscription")
    match oneofcase:
        case "typeSubscription":
            type_subscription_msg: agent_worker_pb2.TypeSubscription = subscription.typeSubscription
            return TypeSubscription(
                topic_type=type_subscription_msg.topic_type,
                agent_type=type_subscription_msg.agent_type,
                id=subscription.id,
            )

        case "typePrefixSubscription":
            type_prefix_subscription_msg: agent_worker_pb2.TypePrefixSubscription = subscription.typePrefixSubscription
            return TypePrefixSubscription(
                topic_type_prefix=type_prefix_subscription_msg.topic_type_prefix,
                agent_type=type_prefix_subscription_msg.agent_type,
                id=subscription.id,
            )
        case None:
            raise ValueError("Invalid subscription message.")

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Pin host and all workers to the same autogen-ext version so the generated protos match
2. If you write a custom servicer, always populate either typeSubscription or typePrefixSubscription before sending
3. Log the raw message (subscription.WhichOneof('subscription')) at the receiving side to confirm which field is missing

Example fix

# before (custom servicer)
sub = agent_worker_pb2.Subscription(id=sid)  # oneof never set

# after
sub = agent_worker_pb2.Subscription(
    id=sid,
    typeSubscription=agent_worker_pb2.TypeSubscription(topic_type="t", agent_type="a"),
)

# On the sender side: verify the oneof is set before sending
assert sub.WhichOneof("subscription") in ("typeSubscription", "typePrefixSubscription"), "malformed Subscription proto"

from autogen_ext.runtimes.grpc._utils import subscription_from_proto
try:
    sub = subscription_from_proto(msg)
except ValueError as e:
    if "Invalid subscription message" in str(e):
        log.warning("dropping malformed subscription from host: %s", msg)
        return None
    raise

When it happens

Trigger: The gRPC host (or another worker) sends an agent_worker_pb2.Subscription whose `subscription` oneof is not populated — e.g. hand-crafted protos, a mismatched proto schema between host and worker, or memory corruption of the message — and this worker tries to deserialize it.

Common situations: Running host and worker on different autogen-ext versions whose protos disagree; a custom host servicer that forgets to set typeSubscription/typePrefixSubscription; fuzzing or manual proto construction in tests.

Related errors

• Unsupported subscription type.
• Unsupported payload serialization format: {payload_serializa
• Unsupported message content type: {message_content_type}
• Tool names must be unique: {tool_names}
• Maximum number of tool iterations must be greater than or eq

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/7f65c301248dc761. Report an issue: GitHub.